Heretofore, generally horizontal roof panels for the collection of solar radiant energy have been constructed by housing parallel rigid black water conduits in cavities defined between opposed translucent corrugated surfaces or plates. In such a construction, because of intimate contact between the conduits and the lower corrugated surface or plate, thermal insulation has been required between the lower plate and the roof to reduce heat leakage. While a flanged rigid solar energy absorbing element carrying a plurality of black water conduits has heretofore been housed centrally between a pair of opposed channel-shaped windows in a single cavity solar collector, for the purpose of being thermally isolated from the windows, such a construction would not be amenable for use between opposed corrugated plates, because of great expense and difficulty of assembly. The simultaneous assembly of a plurality of such elements in the cavities defined between opposed corrugated surfaces is extremely difficult because of the absence of means for longitudinally aligning the elements in the cavities.
Furthermore, rigid thermal energy absorbing elements particularly of the plastic type, have been difficult to utilize between opposed corrugated surfaces, since any bow or warpage in said elements would lead to assembly difficulties and lack of closing of adjoining cavities.